This invention relates generally to control circuits and in particular to a control circuit for varying the speed of an alternating current motor, a refrigeration system utilizing such control circuit, and a method of controlling speed of an alternating current motor.
In the past, many and various types of control circuits have been utilized for varying the speed of a dynamoelectric machine, such as an electric motor. For instance, it is well known in the art to provide a fan driven by an electric motor in a refrigeration system to aid in cooling a condenser coil thereof, and it has been recognized that the efficiency of the refrigeration system may be impared and other problems created if the temperature of the condenser varies generally from a preferred operating range. Further, various systems for sensing condenser temperature and controlling fan motor speed have been utilized in the past to control the condenser temperature, and one related system is disclosed in my copending application Ser. No. 548,764 filed Feb. 10, 1975.